Currently available stereo display devices are generally autostereoscopic displays, i.e. naked eyes three-dimensional (3D) displays. Principally, a beam splitter such as a liquid crystal (LC) lens is added to a two-dimensional (2D) display panel at a light exit so as to have an observer's left and right eyes differentially receive a binocular parallax image shown on a display panel. Combined in the observer's brain, stereo perception can be acquired.
The beam splitter, e.g. the LC lens, is generally fabricated with a lenticular lens array made of transparent material, and by way of refraction therethrough, light is emitted from different pixels in different polarizing directions so as to separate the parallax image. As shown in FIG. 1, which is a schematic diagram showing a structure of an LC lens according to prior art, LC molecules 110a and 120a corresponding to adjacent two strips of electrode sets 110 and 120 tilt in the same way, i.e. the pretilt angles are both 0°, if there is no voltage applied to the LC lens 100. Meanwhile, there is no difference in refraction index between the centers and the edges of the LC layers corresponding to the strip electrode sets 110 and 120, so what the user watches through the LC lens 100 is an image 20 free of parallax.
FIG. 2 is a schematic diagram showing titling configurations of LC molecules when a voltage is applied. Combined FIG. 1 and FIG. 2 show that when a certain voltage is applied to the LC lens 100, differences in refraction index occur between the centers and the edges of the LC layers corresponding to the strip electrode sets 110 and 120 due to the electric field distribution, and the phase distribution similar to a lens can be formed on the condition that a focusing mode is satisfied. Therefore, a user may see a binocular parallax image 20 through the LC lens 100, and a 3D image can be seen at an optimal observing distance.
Since the pretilt angles are the same, all the LC molecules in the LC layer 130 with voltage applied thereto, including LC moculaes 110a and 120a, would tilt along the distribution direction of the electric field. However, due to possible uneven distribution of the electric field and operational factors in practice, it is likely to result in asymmetric tilting of LC molecules corresponding to the two symmetric strip electrode sets 110 and 120. As shown in the figure, the tilting situation of the LC molecules indicated by the dash frames is disordered. As a result, there exists matching deviation between the Neff profile (curve of effective refraction index) L2 and the ideal Neff profile L (see FIG. 3), which deteriorates the light-concentrating property of the display device and thus adversely affects the 3D displaying effect for watching.
In view of the foregoing, there is a need to provide an LC lens and a stereo display device, which exempt from the above problems.